This makes sense as the the problem started around the time LACP support was introduced in ESXi. Unfortunately it has broken the simple originating port ID and LBT teaming when the VC modules are not using LACP. We have each module connected to 1 x 10Gb port on the same switch. Redundancy is provided by a standby 1 GB link on each VC module to a separate switch. ESXi has no visibility of this, the failover is handled at the VC layer. VC is the latest firmware by the way.
All ESXi is aware of is the 2 10Gb uplinks to the same switch. A very simple config that has always worked seamlessly in the past. We are also seeing exactly the same symptoms on our rack hosts that don't use VC. I suspect if we turn LACP on then the problem will disappear. We are however deliberately trying to keep things as simple as possible given the Nightmares we have experienced with Virtual Connect over the last 3 years.
Fundamentally it appears that in introducing LACP to ESXi directly the other options have broken. Ironically we stopped using LACP at the VC modules because it previously broke the ESXi teaming!
Message was edited by: NV1 Added reference to who I am replying to: geeaib824